The mu-opioid receptor (OPRM1) is the primary binding site for many opioid drugs and for binding of beta-endorphins. A number of gene variations have been identified that can influence opioid drugs binding to OPRM1. Patients with the AA genotype who are treated with Naloxone may have lower Cortisol response as compared to patients with the AG or GG genotype. Other genetic and clinical factors may also influence the response to naloxone.

CYP1A2

The CYP1A2 is involved in the metabolism of 8-10% of commonly used drugs including those used for pain management such as Leflunomide as well as natural compounds such as caffeine. A large number of CYP1A2 variants have been identified and have been shown to influence individual’s ability to metabolize certain drugs. The CYP1A2 assay identifies some common variants associated with variability in CYP1A2 enzyme activity and in turn patient’s response to treatment.

CYP2B6

The CYP2B6 is responsible for the metabolism of 4% of the top 200 prescribed drugs, including those used for pain management such as Methadone. A large number of variants have been reported. The CYP2B6 assay identifies some common variants associated with variability in CYP2B6 enzyme activity and patient’s response to treatment.

CYP2C9

The CYP2C9 is involved in the metabolism of 15% of clinically important medications. Examples of such medications used in pain management include Ibuprofen, Aleve, Voltaren, Feldene, Celebrex, Aspirin and Mobic. To date 30 different variants of CYP2C9 have been identified. The CYP2C9 assay identifies some common variants associated with variability in CYP2C9 enzyme activity.

CYP2C19

The CYP2C19 is involved in the metabolism of approximately 10% of clinically relevant medications including some that are prescribed for pain management such as Valium and Soma. To date 30 different variants of CYP2C19 have been identified. The CYP2C9 assay identifies some common variants associated with variability in CYP2C9 enzyme activity in turn patient response to treatment.

CYP2D6

The CYP2D6 is involved in the metabolism of 25% of clinically important medications including the following analgesics: Codeine, Tramadol and Vicodin. To date more than a 100 different variants in CYP2D6 have been identified. The CYP2D6 assay identifies common variants associated with variability in CYP2D6 enzyme activity and in turn patients response to treatment.

CYP3A4

CYP3A4 and 3A5 are involved in the metabolism of approximately 50% of commonly used drugs including drugs used for pain management such as methadone. CYP 3A4 and CYP3A5 enzymes have overlapping substrate specificity and the contribution of CYP3A5 in the overall metabolism is smaller than the one for CYP3A4. The overall CYP3A metabolism status is expected to affect drugs that have narrow therapeutic index. The CYP3A assay tests for the presence of CYP3A genetic variants that can influence its activity.